Berkshire, England: Indigrow developed Diamond Green as a liquid fertiliser based on potassium, calcium and magnesium. It contains essential plant oils to enhance plant health and increase disease resistance in turf grass.

The combination of nutrients in Diamond Green improves the natural resistance of plants to many known pathogens.

After the successful development, the additive formulation, trials of Diamond Green at different application rates were carried out to assess its impact on the spread of Fusarium and Red Thread. It was tested three different application rates to assess its effectiveness.

Diseased turf cores were harvested from infected areas of turf on a parkland golf course. The cores were harvested in late summer 2021 when these diseases were very active. Disease levels were consistent across each core at the time of harvest.

Throughout the trials, Indigrow’s aim was to find out the effectiveness Diamond Green had on different turf grass diseases without killing the fungus.

“As Diamond Green is a fertiliser with additives, it was important for us to show how this formulation would prevent the spread of the fungus within the cores taken from the parkland golf course,” said Brian Croose, Asean Regional Manager for Indigrow, a Full Business Member of the Asian Golf Industry Federation.

The following treatments were tested for their potential to reduce disease spread in already infected turf stands:

The turf cores were harvested for each treatment, one infected with Fusarium Patch and one infected with Red Thread. The cores were then sprayed with each treatment until the turf surface was fully covered.

The treated turf was then sealed in clear boxes to provide the humidity conducive to active disease spread. The development of the disease and the health of the turf was then monitored over the next four to five days.

Over a period of four days, the active Fusarium had spread freely on the untreated turf core and white, active mycelium was observed. The fungicide treatment suppressed the spread of Fusarium, but there was still a small amount of active mycelium present.

At 10 lt/ha, Diamond Green suppressed the spread of Fusarium, but like the fungicide there was still a small amount of active mycelium present.

At both 20 and 40 lt/ha, Diamond Green not only suppressed the spread of Fusarium but allowed the turf to start to fill in disease-scarred areas of turf. There was only a very small amount of active mycelium present on the turf.

Over a period of five days, the active Red Thread spread freely on the untreated turf core and active red areas could be observed.

At only 10 lt/ha, Diamond Green had a limited impact on disease spread. However, at 20 lt/ha, the Red Thread was almost completely suppressed and the turf had a noticeable green up response and there was an obvious increase in growth rate.

Talking about the effect on disease, Croose said: “It’s important to state that Diamond Green is not a fungicide, it’s a fertiliser with additives. We trialled both the fertiliser formulation without additives alongside the full Diamond Green formulation with additives.

“We found that when treated in isolation, the fungal growth is the same for just the fertiliser component as it is for the finished formulation containing the additives.

This confirms that it is the systemic acquired resistance within the plant that stops the spread of the disease.”

As Diamond Green acts as a trigger to the natural defences of plants, rather than having a direct effect on the fungus itself, it is safe to assume that the activity on Fusarium and Red Thread would be similar on other turf grass diseases including: Anthracnose, Dollar Spot, Snow Moulds and Leaf Spot.

Croose said: “The applications of Diamond Green have been successful in reducing the spread of Red Thread and Fusarium and the higher the application rate of Diamond Green, the stronger the effect is on disease.

“At higher application rates of Diamond Green, the treatment also produces a strong growth response, with turf able to quickly ‘fill in’ previously diseased/scarred areas.

“Although this trial was only observational, we have a strong indication that Diamond Green can play a vital role as part of an integrated disease management strategy.

“With the benefits to turf health (shown by increased growth response and improved colour), we predict that turf treated with Diamond Green will have improved resistance to future disease attack.”